Manufacturing a dental implant drill guide and a dental implant superstructure

ABSTRACT

Dental implant drill holes and the shape of a dental implant superstructure are chosen by creating a computer model giving jawbone structural details, gum surface shape information and proposed teeth or dental prosthesis shape information. The computer model shows the bone structure, gum surface and teeth images properly referenced to one another so that implant drill hole positions can be selected taking into consideration proper positioning within the bone as well as proper positioning with respect to the dental prosthesis. Similarly, manufacture of the dental implant superstructure used for fixed dental prosthesis or overdentures can be designed based on knowledge of the actual implant positions referenced to an image of the gum surface and proposed dental prosthesis.

RELATED APPLICATION

[0001] This is a Continuation In Part of U.S. patent application Ser.No. 09/595,921 filed on Jun. 16, 2000, which is a continuation of U.S.Pat. No. 5,725,376 filed on Feb. 26, 1997 and issued on Mar. 10, 1998,and which is, in turn, a continuation of PCT Application No.PCT/CA97/00984.

FIELD OF THE INVENTION

[0002] The present invention relates to a method of manufacturing adental implant drill guide. The invention also relates to a method forthe reconstruction of an edentulous jawbone.

BACKGROUND OF THE INVENTION

[0003] It is known in the art to secure dental prostheses using dentalimplants secured in the upper or lower jawbone. It is also known in theart to mount a framework or superstructure to a number of implants, thesuperstructure being used to evenly support a set of false teeth ordenture prostheses. Accurate placement within the jawbone of theimplants is a difficult task. In International Patent Application No.PCT/IT94/00059, published Nov. 24, 1994 as WO 94/26200, there isdescribed an adjustable guiding device for positioning dental implantsin which it is possible for the dental surgeon to adjust a drill axisfor each implant before proceeding to use the guiding device or drilltemplate to guide the surgeon's drill for the purposes of preparing thedrill hole for the implant. The guiding device disclosed in theInternational publication helps the dental surgeon to decide on thedrill axis after viewing radiographic images of the radio-opaque tubulardrill guide superposed the bone structure.

[0004] In the known prior art, the oral surgeon typically has difficultydeciding on a drill axis for the implants since the ideal position forthe implants should be decided with knowledge of the jawbone structureinto which the implant is to be inserted, knowledge of the positionwithin the jawbone structure of the nerve tissue, the gum surface andthe required position and dimensions of the false teeth or dentures tobe supported by the dental implant. Of course, in the conventionalmanner of selecting the implant axis, the dentist or dental surgeonsimply makes a best guess in light of his knowledge of the patient. Ofcourse, this leads, in certain cases, to imperfections in the dentalprosthesis. The imperfections may be lack of ideal support, unfavorableangulation of an implant causing a weakness in the implant which maycause failure over time, or a visually perceptible defect in theappearance of the prosthesis.

[0005] In the conventional method for the construction of thesuperstructure, a physical model of the patient's gums and dentalimplant heads is prepared on which the superstructure is built manuallyusing molding and other techniques known in the art. The craftsman ortechnician skilled at manufacturing such dental superstructures takesinto consideration the size and shape of the desired dentures to beplaced over the superstructure when crafting the same. The procedure formanufacturing dental implant superstructures as is conventionally knownin the art is time-consuming and sometimes results in imperfectstructures or defects in the visual appearance of the dentures to beplaced over the superstructure.

[0006] In U.S. Pat. No. 5,401,170 granted Mar. 28, 1995 to Nonomura,there is disclosed a method and apparatus for measuring by camera imagethe implant heads of the implants in the patient's mouth for thepurposes of cutting a frame on which the prosthetic teeth will bearranged and baked. In the method disclosed, the construction of theframe or superstructure is carried out in the absence of a reference tothe shape and position of the patient's ideal teeth position. Thus, asthe dentures or artificial teeth are crafted on the frame orsuperstructure, care would be required during the manual process toensure that the position of the teeth on the frame will match theopposed set of teeth in the patient's mouth.

[0007] Known techniques also have the disadvantage of necessitating twoseparate sessions to install the implants and the superstructure. Itwould be highly beneficial to be able to prepare the superstructureprior to the surgery so that the implants and the superstructure areinstalled during the same surgical procedure.

OBJECTS OF THE INVENTION

[0008] It is a first object of the present invention to provide a methodof manufacturing a dental implant drill guide or drill template whichwill result in a precise and accurate drill guide for selected drillholes.

[0009] It is furthermore an object of the present invention to provide amethod of manufacturing a dental implant superstructure in whichinformation concerning the position of a plurality of dental implantsmounted in a jawbone, the gum surface covering the jawbone and the fixeddenture shape is all taken into consideration during the specificationof the shape of the superstructure before the superstructure isprecision made.

[0010] It is yet another object of the present invention to provide suchmethods which provide better accuracy and faster results thanconventional methods.

[0011] It is yet another object of the present invention to provide adental implant drill guide which is precise and easy to use such thatdrilling of the dental implant holes does not require expert skill andknowledge beyond the skill of basic dental surgery. It is furthermore anobject of the present invention to provide tools which will reduce thenumber of visits a patient needs to make to the dental surgeon in orderto have dental implants and a dental implant superstructure inserted.

SUMMARY OF THE INVENTION

[0012] According to a first aspect of the invention, there is provided amethod of manufacturing a dental implant drill guide, comprising thesteps of: imaging a jawbone and tissue structure with a reference to aknown anatomical reference to produce a three-dimensional computergraphics model; selecting at least one implant drill hole position forat least one dental implant using said model, said position beingspecified in three dimensions, including a hole termination point andorientation, and being referenced to said anatomical reference, enteringat least one set of implant drill hole position coordinates into acomputer controlled precision manufacturing device; providing a drilltemplate body having a first surface adapted to overlie a gum surface ofthe jawbone in a single predetermined position; using said precisionmanufacturing device to provide a fixed orientation drill guide socketin said template body for each one of said at least one drill holeposition with a corresponding position and orientation.

[0013] According to a second aspect of the present invention, there isprovided a method for allowing the reconstruction of an edentulousjawbone in a single surgical operation, comprising the steps of: a)creating a three-dimensional graphic computer model of a patient's gum,jawbone and tissue structure, and of a dental prosthesis to be placedover the gum; b) selecting a number of virtual implant drill holespositions for corresponding implants using said model; c) entering datarelated to the virtual implant drill hole positions into a computercontrolled precision manufacturing device; d) providing a rigid drilltemplate body; e) using said precision manufacturing device to provide afixed orientation socket in said drill template body for each one ofsaid implant drill hole positions selected in step b); f) prior to thesurgical operation, using said data on said virtual implant drill holepositions and said precision manufacturing device to make a dentalimplant superstructure having a number of dental implant abuttingflanges interconnected by a bridge in a fixed configuration in whichsaid dental abutting flanges are positioned in accordance with thevirtual implant drill hole positions; g) using said drill guide to drillpilot holes in the patient's jawbone at said virtual implant drill holepositions; h) inserting an implant in each of said pilot holes; and i)installing the dental implant superstructure prefabricated in step f) onthe implants inserted in the patient's jawbone.

[0014] In the method of manufacturing a dental implant drill guideaccording to the present invention, the patient is typically edentured,namely, the patient has had all teeth pulled from the jawbone, and thejawbone has been given time to heal since the teeth were pulled. If thepatient decides to proceed with dental implants and the placement of asuperstructure for solidly securing dentures over the gum, a period ofabout 1 month is provided for from the time of pulling any remainingteeth from the jawbone before proceeding with the operation of insertingimplants into the jawbone.

[0015] A medical image of the jawbone and tissue structure is obtainedby using x-ray imaging, MRI or possibly nuclear imaging techniques toproduce a three-dimensional computer graphics model which has areference to the gum surface or some other fixed reference with respectto the patient's jawbone. Preferably, a radiographic scanner guide isused which is molded to conform to the shape of the patient's gums andwhich includes radio-opaque spheres whose positions with respect to thegum surface is known.

[0016] The primary advantage of the invention is that the oral surgeonmay select the optimum position for dental implants using thethree-dimensional computer graphics model of the jawbone and tissuestructure. Selection of the drill hole positions using the computergraphics model is transferred to a CNC device for the purposes ofproviding fixed drill guide sockets in the template body for each one ofthe drill hole positions or position selected using the computergraphics model. While the model is three-dimensional, it may beconvenient for the purposes of selecting the drill hole axis to use atwo-dimensional representation of the jawbone and tissue structure, thetwo-dimensional view being displayed with a user controlled slice angle.Preferably, the dental surgeon will select the position for each implantdrill hole, not only to position the implant in the optimum locationwithin the jawbone, but also to result in a position of support which issuitable for supporting the dentures. Therefore, it is preferred todisplay, in addition to the three-dimensional computer graphics model ofthe jawbone and tissue structure, the patient's dentures in the properspatial relationship with respect to the jawbone and tissue structure.This requires imaging the patient's dentures or teeth, and possibly gumstructure, in addition to the jawbone and tissue structure, in such away that all images are referenced with respect to one another to beintegrated into the same three-dimensional computer graphics model.

[0017] While it would be possible to prepare the drill template body andprovide it with the drill guide sockets using the CNC device, the drilltemplate body is preferably molded on a physical model of the gumsurface into which model the CNC device has previously drilled thedesired implant drill holes. The drill holes in the physical model areused to build a mold for the drill guide sockets. This prevents the needto use the CNC device to produce fine details except for the precisiondrilling of the drill holes.

[0018] Imaging of the dentures or teeth to be placed over the gumsurface and the imaging of the gum surface can be carried out by usinglaser camera imaging techniques known in the art. These images arepreferably obtained using a physical model of the patient's gum surface,and the physical model is imaged in such a way that the images can bereferenced accurately to the jawbone and tissue structure images.

[0019] According to one method of manufacturing the dental implantsuperstructure, the actual dental implant position data is obtained bytaking an imprint using transfers connected to the implants. Preferably,the imprint is taken using the same drill guide with the sockets of thedrill guide being large enough to receive the transfers and surroundingimprint material. Preferably, the positions and orientations of thetransfers are physically measured along with a reference to the drillguide which will permit the relative positions of the implants to beknown with a reference to a standard frame of reference. Using thestandard frame of reference, it is possible to generate a computergraphics model of the gum surface, dentures or teeth and dental implantswhich allows the dental surgeon or technician to select the best shapefor the overlying bridge of the superstructure.

[0020] According to a further general aspect of the present invention,the implant drill hole positions selected using the computer graphicsmodel can also be used to make the superstructure. By so using theplanned implant positions, instead of taking an imprint of the implantsinserted in the patient's jawbone to precisely determine their actuallocations in relation to the jawbone, the superstructure can be madeprior to the surgical operation, i.e. prior to the insertion of theimplants into the patient's jawbone. This advantageously provides forthe installation of the implants and the superstructure in a singlesurgical operation. This novel approach of creating a superstructure onthe basis of the virtual positions of the dental implants selected usingthe three-dimensional computer graphic model of the jawbone and thedental prosthesis has the following advantages for the surgeon:

[0021] no need for taking imprints of the implants to determine theirpositions in the jawbone;

[0022] no need for a second surgical procedure to expose the head of theimplants;

[0023] improved stability of the implants, as they are immediatelyinterconnected to each other by the superstructure;

[0024] improved protection of the implants, since they are betterstabilized;

[0025] less sessions with a patient, thus, higher profitability;

[0026] and the following advantages for the patient:

[0027] only one operation and, thus, less traumatism;

[0028] accelerated healing because of the protection afforded by thesuperstructure;

[0029] In the case of a fixed dental prosthesis which is implant mounted(i.e. porcelain on metal), the ideal form of the superstructure can beautomatically designed using the computer model taking intoconsideration the form of the laser camera imaged teeth and bysubtracting a thickness of porcelain which the technician requires torecreate the shape of the imaged teeth. In the case of a dentalprosthesis supported by a superstructure (overdenture), the shape of thesuperstructure can be automatically determined by taking into accountthe external shape of the prosthesis and by circulating thesuperstructure inside the prosthesis, making sure that the necessarythickness of prosthesis material (e.g. acrylic) will be available allaround in order to provide a adequately strong prosthesis.

[0030] When precision forming the superstructure, it is possible to usevarious techniques. In one embodiment, the entire superstructure is cutusing a CNC milling machine programmed to cut according to the shapedata specified using the computer model.

BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Other objects and features of the present invention will bebetter understood by way of the following detailed description of thepreferred embodiment with reference to the appended drawings in which:

[0032]FIG. 1 is a perspective view of an articulator supporting aphysical model of a patient's upper and lower gums with dentures inplace;

[0033]FIG. 2 is a perspective view similar to FIG. 1 in which thedentures have been replaced by a radiographic scanning guide;

[0034]FIG. 3 is a perspective view of the radiographic scanning guide;

[0035]FIG. 4 is a perspective view of a three-dimensional computer modelof a patient's lower jawbone shown partly broken away with theradio-opaque reference spheres and reference coordinate superimposed;

[0036]FIG. 5 is a flow diagram of the method of manufacturing the dentalimplant drill guide according to the preferred embodiment;

[0037]FIG. 6 is a panoramic view of a lower jawbone of a patient withthe gum line and dentures superimposed;

[0038]FIG. 7 is a cross-sectional view about line 7 of FIG. 6;

[0039]FIG. 8 is a block diagram of the CNC drill device and data entryterminal;

[0040]FIG. 9 is a perspective view of a five axis CNC drill device;

[0041]FIG. 10 is a front view of a physical model with four drill axesshown;

[0042]FIG. 11 is a view similar to FIG. 10 in which a drill guide hasbeen molded with the fixed drill sockets formed by pins inserted in thedrill holes;

[0043]FIG. 12 is a perspective view of the drill guide according to thepreferred embodiment;

[0044]FIG. 13 is a sectional view of the drill guide being used to drilla patient's jawbone;

[0045]FIG. 14 is an enlarged sectional view of a jawbone having receivedan implant with the drill guide placed on top of the gum surface to actas an impression tray for the purposes of taking an exact imprint of theimplant position using a transfer;

[0046]FIG. 15 is a sectional view of a computer model illustrating thedenture fit over the patient's gums with the implant head in correctrelative position;

[0047]FIG. 16 illustrates a similar computer graphics image as in FIG.15 for a position between two implants;

[0048]FIG. 17 illustrates a perspective view of lower dentures and alower superstructure; and

[0049]FIG. 18 is a view from underneath the assembled componentsillustrated in FIG. 17.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

[0050] As illustrated in FIG. 1, an articulator 20 as is known in theart is set up to support a lower physical model 21 and an upper physicalmodel 22 of a patient's mouth with lower and upper dentures 23 and 24supported by the physical model with the teeth of the dentures in properalignment. The articulator is adjusted using the adjustment means 25 and26 as is known in the art. As illustrated in FIG. 2, the dentures 23 and24 are removed and a scanner guide 27 is made by hand to fit exactly thespace occupied by the upper and lower denture. Radio-opaque referencespheres 28 having a known diameter are bonded to the guide 27 with onesphere on each side at the rear and one in the front. In theillustration in the preferred embodiment, the spheres are shown near thelower jaw surface since it is the lower jaw that is to be imaged. Thespheres could likewise be placed near the upper jaw surface as the casemay be. The separated scanner guide body 27 is illustrated in FIG. 3.

[0051] The particular advantage of the scanner guide 27 according to thepresent invention is that during radiographic scanning of the patient'sjaw, the patient may comfortably hold the scanner guide 27 in place byclosing down on the same. As can be appreciated, the lower jaw couldmove during imaging and must be secured by means such as the scannerguide 27. The patient's head is held in place during radiographicscanning using a suitable brace as is known in the art.

[0052] As shown in FIG. 4, the result of the radiographic scanning is toobtain a three-dimensional computer graphics model 29 of the patient'slower jaw. Images of the reference spheres 28 appear as 33 and provide areference to a coordinate axes 32. The dental surgeon is capable ofviewing with the model 29 the nerve 37 which extends from the base ofthe jaw until it exits the jawbone at each side of the chin. A drillaxis 31 for each proposed drill hole 34 is selected on the computermodel. The end point of the drill hole 36 is also selected.

[0053] For ease of selection of the drill axis 31, namely the positionin space of the end point and the angular orientation of the drill axis31, it may be possible to present slices of the computer model 29 to thedental surgeon or technician which would make it easier to select theparameters. As can be appreciated, two angles are required to specifythe orientation of the drill axis 31, for example, a first angle θ maydefine an angle of the drill axis 31 with respect to the x-z plane and asecond angular parameter φ may define the angle between the drill axis31 in the z-y plane.

[0054] In the preferred embodiment, selection of the drill axes 31 forthe drill holes 34 is done with knowledge of the relative position ofthe gum surface and the relative position of the dentures or teeth. Asillustrated in FIG. 5, the 3-D computer model 29 is built up using theradiographic 3-D imaging data as well as referenced gum surface imagedata and referenced denture image data. In FIG. 6, there is shown apanoramic slice view of the 3-D model 29 showing the gum surface 44 anddentures 43 superposed the cortical bone structure 41 and the marrow 42.

[0055] As illustrated in FIG. 7, in the preferred embodiment, it ispossible to view for a selected drill axis 31 the resulting implantposition 49 and how this relates to the bone structure 41 and 42, thenerve 37, if present, as well as the lower and upper denture structure44 and 43. As can be appreciated, if the desired angle and position ofthe dentures with respect to the gum surface 46 would require anadjustment of. the position and angle of the implant 49, the dentalsurgeon is able to select the optimum depth, position and angularorientation for the implant 49 relying entirely on the computer model.Once the hole termination position and angular orientation data for eachof the drill holes is selected using the computer model, the data isentered through a data entry device 51 to control a CNC drill 52 inaccordance with FIG. 8 and as better illustrated in FIG. 9.

[0056] The CNC drill 52 has a drill bit 53 which is capable of movingand drilling along a first vertical direction 54. The physical model 21is mounted in such a way that it is able to turn about two directions 55and 56 on a platform which is able to move in directions 57 and 60. TheCNC drill 52 is capable of moving about five axes. In order for the CNCdrill device to be properly referenced with respect to the physicalmodel 21, the scanner guide may be placed on top of the physical model21 and a coordinates measuring machine (CMM) connected to CNC drill 52is used to accurately locate the position of each one of the positionreference spheres and reference these to the CNC drill's referenceframe. The CNC drill 52 is then programmed to convert the hole positionand orientation data as referenced to the frame of reference of thecomputer model to the reference frame of the CNC drill so that the drillholes may be prepared in the physical model 21.

[0057] As illustrated in FIG. 10, four drill holes 58 are cut into thephysical model 21 which is mounted on a base 59. The drill hole axes 31as shown are in different positions and orientations.

[0058] As shown in FIG. 11, rods 62 are inserted into the holes 58. Thesocket forming mold parts 63 are placed over the rods 62 and asurrounding mold structure (not shown) is placed around the physicalmodel 21 to allow for the molded guide body 61 to be formed. Since theholes 58 are of different heights, the socket forming mold parts 63 areadjusted in size such that the distance between the circular flange edgeand the end of the rods 102 is a constant. In this way, the circularflange edge 64 of the drill guide sockets is at a fixed distance withrespect to the desired end point of the drill hole.

[0059] As shown in FIG. 12, the finished molded drill guide body 61 hasa plurality of drill guide tubes 66 inserted into the drill guidesockets 68, and three holes 67 are additionally provided fortransitionally securing the drill guide 61 to the patient's jawboneduring surgery. The drill guide tubes 66 may be removed and reinsertedinto the drill guide sockets 68 in order to change the internal diameterof the drill guide tubes as is required during surgery since the implantdrill hole is started with a very small diameter drill bit andsubsequently larger drill bits are used until the full size implantdrill hole is obtained. As shown in FIG. 13, the drill used in surgeryis provided with a collar 69 for abutting against the upper surface ofthe guide tube 66 in such a way that the distance between the bottom ofthe collar 69 and the end of the drill bit 71 is fixed as required. Inthe preferred embodiment, the collar 69 is integral with the drill bit71.

[0060] As can be appreciated, the oral surgeon prepares the implantholes using the drill guide 61 by removing circular portions of the gum(gingival taps) at the implant sites. In the conventional method ofdrilling implant holes, a procedure known as “flap surgery” is carriedout in which a piece of the gum covering the jawbone where the implanthole is to be drilled is cut and peeled back so that the oral surgeonhas clear access to the jawbone surface. Using the present invention,the surgeon has the option of doing flap surgery if required orcircumferential surgery as needed. of course, if a conventional flapsurgery is to be done, a modification of the surgical guide should bedone, i.e. the guide should be removable as needed for flap surgery. Inorder to put the guide back at the same location, the use oftransitional implants is needed to seat the guide after the flap isdone. If the circular approach is chosen, there is no need to remove theguide during surgery, and by avoiding flap surgery, post operationhealing time should be reduced.

[0061] As illustrated in FIG. 14, the oral surgeon screws in an implant72 into the hole made using drill guide 61. This can be done with thedrill guide 61 remaining in place, the implants being inserted throughthe sockets 68. The upper surface of the implant 72 is approximatelyflush with the upper surface of the cortical exterior 41 of the jawbone.The implant 72 has a hollow threaded core. Since the implant 72 has beeninserted into the jawbone tissue 42 by hand, its exact position may notbe perfectly defined by the drill hole formed using the drill guide 61.It has been found that this problem can be overcome by leaving the drillguide 61 in place during the implant insertion and by rigidly connectingeach implant 72 to the guide 61 once fully inserted in the patient'sjawbone. The screwdriver (not shown) used by the surgeon to screw theimplants 72 into the implant holes is provided with a collar forabutting against a corresponding abutting surface (not shown) at theentry of each socket 68 in such a way that the distance between theabutting surface and the bottom of the socket 68 be precisely fixed asrequired. In this way, the surgeon will insert a first implant 72 in oneof the sockets 68 located at a first end of the drill guide 61 and screwthe implant 72 into the corresponding drill hole until the abutment onthe screwdriver contacts the abutment at the entry of the socket 68.Once fully inserted, the implant 72 is securely fixed to the drill guide61 by means of an anchoring screw tightened into the implant 72. Then, asecond implant 72 is inserted into another socket 68 located at a secondend of the drill guide 61 opposite the first end thereof and is screwedinto the corresponding drill hole in the same manner as for the firstimplant 72. A second anchoring screw is then screwed into the secondimplant 72 to rigidly connect the same to the drill guide 61. The otherimplants are subsequently installed following the same procedure. Onceall the implants 72 have been inserted, the relative position of eachimplant 72 with respect to its neighbors should not have changed as longas the drill guide 61 was not subject to any deformations during theinstallation of the implants 72. Indeed, it is important that the drillguide 61 be capable of sustaining elevated torsion forces in order toensure that the actual position of the implants 72 precisely correspondsto that selected on the computer model. For instance, the drill guide 61could be made from a rigid metallic structure or from any otherstructural material offering a high level of rigidity.

[0062] By so using a rigid drill guide in the installation of theimplants, it becomes possible to precisely insert the implants in thepatient's jawbone at the positions selected on the computer model. Thisadvantageously obviates the need for taking an imprint of the implantsto determine their actual positions in view of the fabrication of thesuperstructure to be attached to the implants.

[0063] Due to this new level of precision in the positioning of theimplants, the superstructure can be fabricated prior to the surgeryusing the implant positions selected on the 3-D computer model of thepatient's jawbone, gum and dental prosthesis.

[0064] As shown in FIG. 16, the implant head 49 will receive asuperstructure consisting of an abutment foot 47 extending down to thetop of the implant and having an upper bridge-like structure 48extending inside the lower portion 44 of the denture structure and evenpossibly into the upper portion 43 of the denture structure. In betweentwo implants, as illustrated in FIG. 17, the bridge structure 48 isdesigned to be located above the gum surface 46 and within the denturestructure. As can be appreciated, due to the confines and configurationof the patient's mouth, it may be necessary to shape the bridgestructure 48 such that it passes close to either an inner or outer sidewall of the denture structure 43, 44. In this way, the denturetechnician is capable of viewing in the computer model how the bridgestructure and superstructure is best constructed.

[0065] Once the denture technician has selected the shape for the dentalimplant superstructure and the position of the implants using thecomputer model, the shape data is passed on together with the data onthe selected implant positions to a precision-forming device for shapingthe superstructure. In the preferred embodiment, a CNC milling machinesimilar to the CNC drill device illustrated in FIG. 9 is used. Theresult is a superstructure, as illustrated in FIG. 17, that can befastened directly to the dental implants in a one-stage surgicalprocedure. That is to say, the implants and the pre-manufacturedsuperstructure can be installed during the same surgical procedure.Since the abutment feet 47 of the superstructure and the sockets 68 inthe drill guide 61 are machined using the same virtual implant positiondata and since the implants 72 are prevented from moving in thepatient's jawbone by the drill guide 61, the abutment feet 47 will fitperfectly on the implants 72 screwed into the patient's jawbone, therebyallowing the superstructure to be prepared before the implants 72 areactually inserted into the patient's jawbone.

[0066] The superstructure illustrated in FIG. 17 is of the type whichreceives dentures by snap-fit. The superstructure is prepared from asolid piece of commercially pure titanium or any biocompatible materialsuch as porcelain, preventing corrosion between implants andsuperstructure.

1. A method of manufacturing a dental implant drill guide, comprisingthe steps of: a) imaging a jawbone and tissue structure with a referenceto a known anatomical reference to produce a three-dimensional computergraphics model; b) selecting at least one implant drill hole positionfor at least one dental implant using said model, said position beingspecified in three dimensions, including a hole termination point andorientation, and being referenced to said anatomical reference, c)entering at least one set of implant drill hole position coordinatesinto a computer controlled precision manufacturing device; d) providinga drill template body having a first surface adapted to overlie a gumsurface of the jawbone in a single predetermined position; e) using saidprecision manufacturing device to provide a fixed orientation drillguide socket in said template body for each one of said at least onedrill hole position entered in step (c) with a corresponding positionand orientation.
 2. The method as claimed in claim 1, further comprisingimaging denture prosthesis and including an image of said dentureprosthesis in said model such that a position of said prosthesis withrespect to said jawbone can be seen, whereby said at least one implantdrill hole position can be selected taking into account a position ofsaid denture prosthesis with respect to said jawbone and tissuestructure.
 3. The method as claimed in claim 1, wherein said drill guidesocket receives drill guide tubes having a variable internal diameter.4. The method as claimed in claim 1, wherein said step (e) comprisesdrilling said implant drill holes into the drill guide supported on aphysical model, and forming abutment surfaces on said drill guide on thebasis of said implant drill hole position coordinates.
 5. The method asclaimed in claim 1, wherein said anatomical reference is said gumsurface, and wherein said step (a) comprises preparing a scannerreference guide and carrying out radiographic imaging of said jawboneand tissue structure with said scanner reference guide secured withrespect to said gum surface, and converting said radiographic imaginginto data to produce said three-dimensional computer graphics model. 6.The method as claimed in claim 1, wherein step (b) comprises selectingat least two implant drill hole positions for at least two dentalimplants using said model, step (c) comprises entering at least two setsof implant drill hole position coordinates, and step (e) comprises usingsaid precision manufacturing device to provide a fixed orientation drillguide socket in said template body for each one of said at least twodrill hole positions.
 7. A dental implant drill guide manufacturedaccording to the method defined in claim
 1. 8. The dental implant drillguide as claimed in claim 7, further comprising a plurality of holes fortransitionally securing the drill guide to the patient's jawbone duringsurgery.
 9. A method for allowing the reconstruction of an edentulousjawbone in a single surgical operation, comprising the steps of: a)creating a three-dimensional graphic computer model of a patient's gum,jawbone and tissue structure, and of a dental prosthesis to be placedover the gum; b) selecting a number of virtual implant drill holespositions for corresponding implants using said model; c) entering datarelated to the virtual implant drill hole positions into a computercontrolled precision manufacturing device; d) providing a rigid drilltemplate body; e) using said precision manufacturing device to provide afixed orientation socket in said drill template body for each one ofsaid implant drill hole positions selected in step b); f) prior to thesurgical operation, using said data on said virtual implant drill holepositions and said precision manufacturing device to make a dentalimplant superstructure having a number of dental implant abuttingflanges interconnected by a bridge in a fixed configuration in whichsaid dental abutting flanges are positioned in accordance with thevirtual implant drill hole positions; g) using said drill guide to drillpilot holes in the patient's jawbone at said virtual implant drill holepositions; h) inserting an implant in each of said pilot holes; and i)installing the dental implant superstructure prefabricated in step f) onthe implants inserted in the patients' jawbone.
 10. A method as definedin claim 9, wherein the implants are inserted with the drill guideremaining in place over the patient's gum, and further comprisingfixedly securing each implant to the drill guide after each implant hasbeen inserted into the patient's jawbone.
 11. A method as defined inclaim 9, wherein step h) is effected by providing a screwdriver, andscrewing each implant into the patient's jawbone until an abutment onthe screwdriver abuts a cooperating abutment at an entry of each socketof said drill guide.